NUMBERS09 File

Files with a .numbers09 file extension are spreadsheet documents which are generated by Apple's "Numbers" application in versions 2.0, 2.1, 2.2 and 2.3 (these versions of the software were released between 2009-2012).

This is distinct from the numbers file produced by more modern versions of iWork.

Numbers forms part of Apple's iWork office suite, a set of applications which run on the Mac OS X and iOS operating systems, and also includes Pages (for word processing) and Keynote (for presentations).

Numbers was first released by Apple in August 2007 and allows users to perform basic spreadsheet tasks, including the manipulation of rows, columns, graphs, formulas and charts.

At the top level iWork '09 numbers files are actually a zip file containing:

An index.xml file

A buildVersionHistory file

A "QuickLook" directory with a "Thumbnail.jpg" of the document. The directory may also contain a PDF file named "Preview.pdf" if the user chose to save the original document with additional preview information in Numbers.

The index.xml is the core component of the file, containing the document content and all of the metadata for formatting it.

Similar to Microsoft products, the .numbers file type suffers from a lack of compatibility with other leading spreadsheet programs.